+/// (i8,i32 {s/z}ext ({s/u}divrem (i8 x, i8 y)) ->
+/// (i8,i32 ({s/u}divrem_sext_hreg (i8 x, i8 y)
+/// This exposes the {s/z}ext to the sdivrem lowering, so that it directly
+/// extends from AH (which we otherwise need to do contortions to access).
+static SDValue getDivRem8(SDNode *N, SelectionDAG &DAG) {
+ SDValue N0 = N->getOperand(0);
+ auto OpcodeN = N->getOpcode();
+ auto OpcodeN0 = N0.getOpcode();
+ if (!((OpcodeN == ISD::SIGN_EXTEND && OpcodeN0 == ISD::SDIVREM) ||
+ (OpcodeN == ISD::ZERO_EXTEND && OpcodeN0 == ISD::UDIVREM)))
+ return SDValue();
+
+ EVT VT = N->getValueType(0);
+ EVT InVT = N0.getValueType();
+ if (N0.getResNo() != 1 || InVT != MVT::i8 || VT != MVT::i32)
+ return SDValue();
+
+ SDVTList NodeTys = DAG.getVTList(MVT::i8, VT);
+ auto DivRemOpcode = OpcodeN0 == ISD::SDIVREM ? X86ISD::SDIVREM8_SEXT_HREG
+ : X86ISD::UDIVREM8_ZEXT_HREG;
+ SDValue R = DAG.getNode(DivRemOpcode, SDLoc(N), NodeTys, N0.getOperand(0),
+ N0.getOperand(1));
+ DAG.ReplaceAllUsesOfValueWith(N0.getValue(0), R.getValue(0));
+ return R.getValue(1);
+}
+